1. Field of the Invention
The present invention relates to a silver halide emulsion containing high silver chloride particles including silver iodide, particularly, high silver chloride tabular particles and further high silver chloride tabular particles having a {111} plane as a principal plane (hereinafter referred to as {111} high silver chloride tabular particle). The present invention also relates to a color photographic light-sensitive material and an image forming method using the silver halide emulsion. The present invention relates, particularly, to an emulsion which has excellent grain shape stability, in which there is little the increase of fogging after a coating solution is dissolved and aged, and has high sensitivity and excellent reciprocity properties (especially, exposure at high illuminance). Also, the present invention relates to a color photographic light-sensitive material using such an emulsion and to a method of forming an image on the color photographic light-sensitive material, and, particularly, to a method of forming an image by exposure performed at high illuminance in a short period of time.
2. Description of Related Art
As a method of forming a tabular silver halide emulsion particle having a {111} principal plane, methods of forming a particle in the presence of a crystal habit control agent comprising, for example, aminoazaindene, triaminopyrimidine, hydroxyaminoazine, thiourea, xanthonoid and a pyridinium salt are disclosed in, for example, U.S. Pat. Nos. 4,400,463, 5,185,239 and 5,176,991, Japanese Patent application Laid-Open (JP-A) No. 63-213836 and U.S. Pat. Nos. 5,176,992 and 5,691,128 respectively.
It is well-known in the fields concerned that, in high silver chloride particles, the {100} plane has tended to appear selectively so that the high silver chloride particles generally have a cubic form. In the above patents, the originally unstable {111} plane is made to appear externally by the crystal habit control agent to form the tabular particle. Therefore, the high silver chloride {111} tabular particle is redissolved immediately after the crystal habit control agent falls away from the surface of the particle, leading to the emergence of the {100} plane, so that the form of the {111} particle cannot be kept. Also, high sensitization by spectral sensitization and chemical sensitization cannot be expected without the fall of the crystal habit control agent.
U.S. Pat. No. 5,691,128 discloses that the adhesion of a crystal habit control agent is controlled by the pH to adsorb a sensitizing dye and the crystal habit control agent such that the both are exchangeable with each other, thereby making shape stability and high sensitization compatible with each other.
Also, U.S. Pat. No. 5,272,052 discloses that silver bromide is selectively formed on the top of particles by epitaxial growth utilizing the adsorption of a crystal habit control agent, and thereafter a photographically useful compound is exchanged with the crystal habit control agent and adsorbed, whereby complex particles consisting of a host and an epitaxial portion can be formed.
However, in a state in which the crystal habit control agent has fallen away, shape and pigment adsorbing conditions in these epitaxial particles changes moment by moment after spectral sensitization and chemical sensitization, and eventually after coating and aging of the coating solution, whereby increase in fogging becomes marked and no epitaxial particles that can be put to use are obtained.
It is generally said in the fields concerned that if a high silver chloride particle is doped with a the compound of a metal from column VIII of the periodic table which metal is represented by iridium, high illuminance reciprocity is improved. However, this is limited to cases in which a sufficient amount of time has lapsed from exposure until development processing. When the amount of time that has lapsed from exposure until development processing is short, there is an increase in the dependency of sensitivity (gradation) on time, and the sensitivity is low (soft). Thus, this does not amount to a measure for improvement. Therefore, in JP-A No. 64-26837, JP-A No. 5-61136, JP-A No. 6-35147, JP-A No. 11-109534, U.S. Pat. Nos. 5,284,745, 5,391,471, 5,415,991, 5,043,256, 5,627,020 and 5,356,770 and European Pat. No. 0568091A, many methods are disclosed in which a silver bromide localized phase is provided in a high silver chloride particle, and the localized phase is intensively doped with a metal compound, whereby high illuminance reciprocity and the dependency of sensitivity on time from exposure until development processing is improved. Particularly in JP-A No. 11-109534, an even greater effect of improvement is achieved by limiting doping of the iridium to within the silver bromide localized phase. However, this doping technique relates to doping the inside of the silver bromide epitaxial, and the shapes of epitaxial particles in the case of {111} high silver chloride tabular particles are unstable. In particular, increased fogging resulting from dissolution and aging of the coating solution cannot be suppressed.
It is an object of the present invention to provide a high silver chloride emulsion including silver iodide to control increase in fogging after a coating solution is dissolved and aged, with which high silver chloride emulsion sensitivity and contrast and illumination reciprocity are improved. In particular, it is an object of the present invention to provide a {111} high silver chloride tabular particle emulsion, a photographic light-sensitive material and an image forming method that each use the {111} high silver chloride tabular particle emulsion.
The inventors of the present invention have found that the above problem can be efficiently solved by using the following means.
Accordingly, the present invention provides a silver halide emulsion comprising high silver chloride particles, the high silver chloride particles having a continuous outermost layer containing at least 30 mol % of silver bromide, the high silver chloride particles having a silver chloride content of at least 95 mol % and a silver iodide content of 0.05 mol % to 0.75 mol %, wherein the outermost layer has a center portion, the center portion being limited to a region within 10% to 90% of the volume of the outermost layer, the center portion having present therein a compound of a metal from column VIII of the periodic table.
Also, the present invention provides a silver halide emulsion comprising tabular particles, the tabular particles occupying at least 50% of a total projected area of all particles, taking a {111} surface as a principal plane, and having an aspect ratio of at least 2.0, the tabular particles being disposed with an outermost layer containing at least 30 mol % of silver bromide, tabular particles having a silver chloride content of at least 95 mol % and a silver iodide content of 0.05 mol % to 0.75 mol %, wherein the outermost layer have a center portion, the center portion being limited to a region within 10% to 90% of the volume of the outermost layer, the center portion having present therein a compound of a metal from column VIII of the periodic table.
Further, the present invention provides a silver halide color photographic light-sensitive material comprising a support having disposed thereon at least a silver halide emulsion layer containing a yellow dye-forming coupler, a silver halide emulsion layer containing a magenta dye-forming coupler and a silver halide emulsion layer containing a cyan dye-forming coupler, wherein at least one of the silver halide emulsions comprises high silver chloride particles, the high silver chloride particles having a continuous outermost layer containing at least 30 mol % of silver bromide, the high silver chloride particles having a silver chloride content of at least 95 mol % and a silver iodide content of 0.05 mol % to 0.75 mol %, wherein the outermost layer has a center portion, the center portion being limited to a region within 10% to 90% of the volume of the outermost layer, the center portion having present therein a compound of a metal from column VIII of the periodic table.
Moreover, the present invention provides a silver halide color photographic light-sensitive material comprising a support having disposed thereon at least a silver halide emulsion layer containing a yellow dye-forming coupler, a silver halide emulsion layer containing a magenta dye-forming coupler and a silver halide emulsion layer containing a cyan dye-forming coupler, wherein at least one of the silver halide emulsions comprises tabular particles, the tabular particles occupying at least 50% of a total projected area of all particles, taking a {111} surface as a principal plane, and having an aspect ratio of at least 2.0, wherein the tubular particles are disposed with an outermost layer containing at least 30 mol % of silver bromide, the tabular particles having a silver chloride content of at least 95 mol % and a silver iodide content of 0.05 mol % to 0.75 mol %, the outermost layer having a center portion, the center portion being limited to a region within 10% to 90% of the volume of the outermost layer, the center portion having present therein a compound of a metal from column VIII of the periodic table.
In addition, the present invention provides an image forming method comprising scan-exposing a silver halide color photographic light-sensitive material and thereafter conducting color development processing, the silver halide color photographic light-sensitive material comprising a support having disposed thereon at least a silver halide emulsion layer containing a yellow dye-forming coupler, a silver halide emulsion layer containing a magenta dye-forming coupler and a silver halide emulsion layer containing a cyan dye-forming coupler, wherein at least one of the silver halide emulsions comprises high silver chloride particles, the high silver chloride particles having a continuous outermost layer containing at least 30 mol % of silver bromide, the high silver chloride particles having a silver chloride content of at least 95 mol % and a silver iodide content of 0.05 mol % to 0.75 mol %, wherein the outermost layer has a center portion, the center portion being limited to a region within 10% to 90% of the volume of the outermost layer, the center portion having present therein a compound of a metal from column VIII of the periodic table.
Further, the present invention provides an image forming method comprising scan-exposing a silver halide color photographic light-sensitive material and thereafter conducting color development processing, the silver halide color photographic light-sensitive material comprising a support having disposed thereon at least a silver halide emulsion layer containing a yellow dye-forming coupler, a silver halide emulsion layer containing a magenta dye-forming coupler and a silver halide emulsion layer containing a cyan dye-forming coupler, wherein at least one of the silver halide emulsions comprises tabular particles, the tabular particles occupying at least 50% of a total projected area of all particles, taking a {111} surface as a principal plane, and having an aspect ratio of at least 2.0, wherein the tabular particles are disposed with an outermost layer containing at least 30 mol % of silver bromide, the tabular particles having a silver chloride content of at least 95 mol % and a silver iodide content of 0.05 mol % to 0.75 mol %, the outermost layer having a center portion, the center portion being limited to a region within 10% to 90% of the volume of the outermost layer, the center portion having present therein a compound of a metal from column VIII of the periodic table.